/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package aria.apache.commons.net.util;

import java.io.UnsupportedEncodingException;
import java.math.BigInteger;

/**
 * Provides Base64 encoding and decoding as defined by RFC 2045.
 *
 * <p>
 * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045
 * <cite>Multipurpose
 * Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and
 * Borenstein.
 * </p>
 * <p>
 * The class can be parameterized in the following manner with various constructors:
 * <ul>
 * <li>URL-safe mode: Default off.</li>
 * <li>Line length: Default 76. Line length that aren't multiples of 4 will still essentially end up
 * being multiples of
 * 4 in the encoded data.
 * <li>Line separator: Default is CRLF ("\r\n")</li>
 * </ul>
 * <p>
 * Since this class operates directly on byte streams, and not character streams, it is hard-coded
 * to only encode/decode
 * character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1,
 * Windows-1252, UTF-8, etc).
 * </p>
 *
 * @version $Id: Base64.java 1697293 2015-08-24 01:01:00Z sebb $
 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
 * @since 2.2
 */
public class Base64 {
  private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;

  private static final int DEFAULT_BUFFER_SIZE = 8192;

  /**
   * Chunk size per RFC 2045 section 6.8.
   *
   * <p>
   * The {@value} character limit does not count the trailing CRLF, but counts all other characters,
   * including any
   * equal signs.
   * </p>
   *
   * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
   */
  static final int CHUNK_SIZE = 76;

  /**
   * Chunk separator per RFC 2045 section 2.1.
   *
   * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
   */
  private static final byte[] CHUNK_SEPARATOR = { '\r', '\n' };

  private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];

  /**
   * This array is a lookup table that translates 6-bit positive integer index values into their
   * "Base64 Alphabet"
   * equivalents as specified in Table 1 of RFC 2045.
   *
   * Thanks to "commons" project in ws.apache.org for this code.
   * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
   */
  private static final byte[] STANDARD_ENCODE_TABLE = {
      'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S',
      'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
      'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4',
      '5', '6', '7', '8', '9', '+', '/'
  };

  /**
   * This is a copy of the STANDARD_ENCODE_TABLE above, but with + and /
   * changed to - and _ to make the encoded Base64 results more URL-SAFE.
   * This table is only used when the Base64's mode is set to URL-SAFE.
   */
  private static final byte[] URL_SAFE_ENCODE_TABLE = {
      'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S',
      'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
      'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4',
      '5', '6', '7', '8', '9', '-', '_'
  };

  /**
   * Byte used to pad output.
   */
  private static final byte PAD = '=';

  /**
   * This array is a lookup table that translates Unicode characters drawn from the "Base64
   * Alphabet" (as specified in
   * Table 1 of RFC 2045) into their 6-bit positive integer equivalents. Characters that are not in
   * the Base64
   * alphabet but fall within the bounds of the array are translated to -1.
   *
   * Note: '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder
   * seamlessly handles both
   * URL_SAFE and STANDARD base64. (The encoder, on the other hand, needs to know ahead of time what
   * to emit).
   *
   * Thanks to "commons" project in ws.apache.org for this code.
   * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
   */
  private static final byte[] DECODE_TABLE = {
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62,
      -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5,
      6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1,
      63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,
      47, 48, 49, 50, 51
  };

  /** Mask used to extract 6 bits, used when encoding */
  private static final int MASK_6BITS = 0x3f;

  /** Mask used to extract 8 bits, used in decoding base64 bytes */
  private static final int MASK_8BITS = 0xff;

  // The static final fields above are used for the original static byte[] methods on Base64.
  // The private member fields below are used with the new streaming approach, which requires
  // some state be preserved between calls of encode() and decode().

  /**
   * Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE above remains static
   * because it is able
   * to decode both STANDARD and URL_SAFE streams, but the encodeTable must be a member variable so
   * we can switch
   * between the two modes.
   */
  private final byte[] encodeTable;

  /**
   * Line length for encoding. Not used when decoding. A value of zero or less implies no chunking
   * of the base64
   * encoded data.
   */
  private final int lineLength;

  /**
   * Line separator for encoding. Not used when decoding. Only used if lineLength > 0.
   */
  private final byte[] lineSeparator;

  /**
   * Convenience variable to help us determine when our buffer is going to run out of room and needs
   * resizing.
   * <code>decodeSize = 3 + lineSeparator.length;</code>
   */
  private final int decodeSize;

  /**
   * Convenience variable to help us determine when our buffer is going to run out of room and needs
   * resizing.
   * <code>encodeSize = 4 + lineSeparator.length;</code>
   */
  private final int encodeSize;

  /**
   * Buffer for streaming.
   */
  private byte[] buffer;

  /**
   * Position where next character should be written in the buffer.
   */
  private int pos;

  /**
   * Position where next character should be read from the buffer.
   */
  private int readPos;

  /**
   * Variable tracks how many characters have been written to the current line. Only used when
   * encoding. We use it to
   * make sure each encoded line never goes beyond lineLength (if lineLength > 0).
   */
  private int currentLinePos;

  /**
   * Writes to the buffer only occur after every 3 reads when encoding, an every 4 reads when
   * decoding. This variable
   * helps track that.
   */
  private int modulus;

  /**
   * Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this Base64
   * object becomes useless,
   * and must be thrown away.
   */
  private boolean eof;

  /**
   * Place holder for the 3 bytes we're dealing with for our base64 logic. Bitwise operations store
   * and extract the
   * base64 encoding or decoding from this variable.
   */
  private int x;

  /**
   * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
   * <p>
   * When encoding the line length is 76, the line separator is CRLF, and the encoding table is
   * STANDARD_ENCODE_TABLE.
   * </p>
   *
   * <p>
   * When decoding all variants are supported.
   * </p>
   */
  public Base64() {
    this(false);
  }

  /**
   * Creates a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.
   * <p>
   * When encoding the line length is 76, the line separator is CRLF, and the encoding table is
   * STANDARD_ENCODE_TABLE.
   * </p>
   *
   * <p>
   * When decoding all variants are supported.
   * </p>
   *
   * @param urlSafe if <code>true</code>, URL-safe encoding is used. In most cases this should be
   * set to
   * <code>false</code>.
   * @since 1.4
   */
  public Base64(boolean urlSafe) {
    this(CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe);
  }

  /**
   * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
   * <p>
   * When encoding the line length is given in the constructor, the line separator is CRLF, and the
   * encoding table is
   * STANDARD_ENCODE_TABLE.
   * </p>
   * <p>
   * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in
   * the encoded data.
   * </p>
   * <p>
   * When decoding all variants are supported.
   * </p>
   *
   * @param lineLength Each line of encoded data will be at most of the given length (rounded down
   * to nearest multiple of 4).
   * If {@code lineLength <= 0}, then the output will not be divided into lines (chunks). Ignored
   * when decoding.
   * @since 1.4
   */
  public Base64(int lineLength) {
    this(lineLength, CHUNK_SEPARATOR);
  }

  /**
   * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
   * <p>
   * When encoding the line length and line separator are given in the constructor, and the encoding
   * table is
   * STANDARD_ENCODE_TABLE.
   * </p>
   * <p>
   * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in
   * the encoded data.
   * </p>
   * <p>
   * When decoding all variants are supported.
   * </p>
   *
   * @param lineLength Each line of encoded data will be at most of the given length (rounded down
   * to nearest multiple of 4).
   * If {@code lineLength <= 0}, then the output will not be divided into lines (chunks). Ignored
   * when decoding.
   * @param lineSeparator Each line of encoded data will end with this sequence of bytes.
   * @throws IllegalArgumentException Thrown when the provided lineSeparator included some base64
   * characters.
   * @since 1.4
   */
  public Base64(int lineLength, byte[] lineSeparator) {
    this(lineLength, lineSeparator, false);
  }

  /**
   * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
   * <p>
   * When encoding the line length and line separator are given in the constructor, and the encoding
   * table is
   * STANDARD_ENCODE_TABLE.
   * </p>
   * <p>
   * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in
   * the encoded data.
   * </p>
   * <p>
   * When decoding all variants are supported.
   * </p>
   *
   * @param lineLength Each line of encoded data will be at most of the given length (rounded down
   * to nearest multiple of 4).
   * If {@code lineLength <= 0}, then the output will not be divided into lines (chunks). Ignored
   * when decoding.
   * @param lineSeparator Each line of encoded data will end with this sequence of bytes.
   * @param urlSafe Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is
   * only applied to encode
   * operations. Decoding seamlessly handles both modes.
   * @throws IllegalArgumentException The provided lineSeparator included some base64 characters.
   * That's not going to work!
   * @since 1.4
   */
  public Base64(int lineLength, byte[] lineSeparator, boolean urlSafe) {
    if (lineSeparator == null) {
      lineLength = 0;  // disable chunk-separating
      lineSeparator = EMPTY_BYTE_ARRAY;  // this just gets ignored
    }
    this.lineLength = lineLength > 0 ? (lineLength / 4) * 4 : 0;
    this.lineSeparator = new byte[lineSeparator.length];
    System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
    if (lineLength > 0) {
      this.encodeSize = 4 + lineSeparator.length;
    } else {
      this.encodeSize = 4;
    }
    this.decodeSize = this.encodeSize - 1;
    if (containsBase64Byte(lineSeparator)) {
      String sep = newStringUtf8(lineSeparator);
      throw new IllegalArgumentException(
          "lineSeperator must not contain base64 characters: [" + sep + "]");
    }
    this.encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
  }

  /**
   * Returns our current encode mode. True if we're URL-SAFE, false otherwise.
   *
   * @return true if we're in URL-SAFE mode, false otherwise.
   * @since 1.4
   */
  public boolean isUrlSafe() {
    return this.encodeTable == URL_SAFE_ENCODE_TABLE;
  }

  /**
   * Returns true if this Base64 object has buffered data for reading.
   *
   * @return true if there is Base64 object still available for reading.
   */
  boolean hasData() {
    return this.buffer != null;
  }

  /**
   * Returns the amount of buffered data available for reading.
   *
   * @return The amount of buffered data available for reading.
   */
  int avail() {
    return buffer != null ? pos - readPos : 0;
  }

  /** Doubles our buffer. */
  private void resizeBuffer() {
    if (buffer == null) {
      buffer = new byte[DEFAULT_BUFFER_SIZE];
      pos = 0;
      readPos = 0;
    } else {
      byte[] b = new byte[buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
      System.arraycopy(buffer, 0, b, 0, buffer.length);
      buffer = b;
    }
  }

  /**
   * Extracts buffered data into the provided byte[] array, starting at position bPos, up to a
   * maximum of bAvail
   * bytes. Returns how many bytes were actually extracted.
   *
   * @param b byte[] array to extract the buffered data into.
   * @param bPos position in byte[] array to start extraction at.
   * @param bAvail amount of bytes we're allowed to extract. We may extract fewer (if fewer are
   * available).
   * @return The number of bytes successfully extracted into the provided byte[] array.
   */
  int readResults(byte[] b, int bPos, int bAvail) {
    if (buffer != null) {
      int len = Math.min(avail(), bAvail);
      if (buffer != b) {
        System.arraycopy(buffer, readPos, b, bPos, len);
        readPos += len;
        if (readPos >= pos) {
          buffer = null;
        }
      } else {
        // Re-using the original consumer's output array is only
        // allowed for one round.
        buffer = null;
      }
      return len;
    }
    return eof ? -1 : 0;
  }

  /**
   * Sets the streaming buffer. This is a small optimization where we try to buffer directly to the
   * consumer's output
   * array for one round (if the consumer calls this method first) instead of starting our own
   * buffer.
   *
   * @param out byte[] array to buffer directly to.
   * @param outPos Position to start buffering into.
   * @param outAvail Amount of bytes available for direct buffering.
   */
  void setInitialBuffer(byte[] out, int outPos, int outAvail) {
    // We can re-use consumer's original output array under
    // special circumstances, saving on some System.arraycopy().
    if (out != null && out.length == outAvail) {
      buffer = out;
      pos = outPos;
      readPos = outPos;
    }
  }

  /**
   * <p>
   * Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least
   * twice: once with
   * the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been
   * reached, so flush last
   * remaining bytes (if not multiple of 3).
   * </p>
   * <p>
   * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
   * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
   * </p>
   *
   * @param in byte[] array of binary data to base64 encode.
   * @param inPos Position to start reading data from.
   * @param inAvail Amount of bytes available from input for encoding.
   */
  void encode(byte[] in, int inPos, int inAvail) {
    if (eof) {
      return;
    }
    // inAvail < 0 is how we're informed of EOF in the underlying data we're
    // encoding.
    if (inAvail < 0) {
      eof = true;
      if (buffer == null || buffer.length - pos < encodeSize) {
        resizeBuffer();
      }
      switch (modulus) {
        case 1:
          buffer[pos++] = encodeTable[(x >> 2) & MASK_6BITS];
          buffer[pos++] = encodeTable[(x << 4) & MASK_6BITS];
          // URL-SAFE skips the padding to further reduce size.
          if (encodeTable == STANDARD_ENCODE_TABLE) {
            buffer[pos++] = PAD;
            buffer[pos++] = PAD;
          }
          break;

        case 2:
          buffer[pos++] = encodeTable[(x >> 10) & MASK_6BITS];
          buffer[pos++] = encodeTable[(x >> 4) & MASK_6BITS];
          buffer[pos++] = encodeTable[(x << 2) & MASK_6BITS];
          // URL-SAFE skips the padding to further reduce size.
          if (encodeTable == STANDARD_ENCODE_TABLE) {
            buffer[pos++] = PAD;
          }
          break;
        default:
          break;  // other values ignored
      }
      if (lineLength > 0 && pos > 0) {
        System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
        pos += lineSeparator.length;
      }
    } else {
      for (int i = 0; i < inAvail; i++) {
        if (buffer == null || buffer.length - pos < encodeSize) {
          resizeBuffer();
        }
        modulus = (++modulus) % 3;
        int b = in[inPos++];
        if (b < 0) {
          b += 256;
        }
        x = (x << 8) + b;
        if (0 == modulus) {
          buffer[pos++] = encodeTable[(x >> 18) & MASK_6BITS];
          buffer[pos++] = encodeTable[(x >> 12) & MASK_6BITS];
          buffer[pos++] = encodeTable[(x >> 6) & MASK_6BITS];
          buffer[pos++] = encodeTable[x & MASK_6BITS];
          currentLinePos += 4;
          if (lineLength > 0 && lineLength <= currentLinePos) {
            System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
            pos += lineSeparator.length;
            currentLinePos = 0;
          }
        }
      }
    }
  }

  /**
   * <p>
   * Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at
   * least twice: once
   * with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been
   * reached. The "-1"
   * call is not necessary when decoding, but it doesn't hurt, either.
   * </p>
   * <p>
   * Ignores all non-base64 characters. This is how chunked (e.g. 76 character) data is handled,
   * since CR and LF are
   * silently ignored, but has implications for other bytes, too. This method subscribes to the
   * garbage-in,
   * garbage-out philosophy: it will not check the provided data for validity.
   * </p>
   * <p>
   * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
   * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
   * </p>
   *
   * @param in byte[] array of ascii data to base64 decode.
   * @param inPos Position to start reading data from.
   * @param inAvail Amount of bytes available from input for encoding.
   */
  void decode(byte[] in, int inPos, int inAvail) {
    if (eof) {
      return;
    }
    if (inAvail < 0) {
      eof = true;
    }
    for (int i = 0; i < inAvail; i++) {
      if (buffer == null || buffer.length - pos < decodeSize) {
        resizeBuffer();
      }
      byte b = in[inPos++];
      if (b == PAD) {
        // We're done.
        eof = true;
        break;
      } else {
        if (b >= 0 && b < DECODE_TABLE.length) {
          int result = DECODE_TABLE[b];
          if (result >= 0) {
            modulus = (++modulus) % 4;
            x = (x << 6) + result;
            if (modulus == 0) {
              buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
              buffer[pos++] = (byte) ((x >> 8) & MASK_8BITS);
              buffer[pos++] = (byte) (x & MASK_8BITS);
            }
          }
        }
      }
    }

    // Two forms of EOF as far as base64 decoder is concerned: actual
    // EOF (-1) and first time '=' character is encountered in stream.
    // This approach makes the '=' padding characters completely optional.
    if (eof && modulus != 0) {
      x = x << 6;
      switch (modulus) {
        case 2:
          x = x << 6;
          buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
          break;
        case 3:
          buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
          buffer[pos++] = (byte) ((x >> 8) & MASK_8BITS);
          break;
        default:
          break;  // other values ignored
      }
    }
  }

  /**
   * Returns whether or not the <code>octet</code> is in the base 64 alphabet.
   *
   * @param octet The value to test
   * @return <code>true</code> if the value is defined in the the base 64 alphabet,
   * <code>false</code> otherwise.
   * @since 1.4
   */
  public static boolean isBase64(byte octet) {
    return octet == PAD || (octet >= 0 && octet < DECODE_TABLE.length && DECODE_TABLE[octet] != -1);
  }

  /**
   * Tests a given byte array to see if it contains only valid characters within the Base64
   * alphabet. Currently the
   * method treats whitespace as valid.
   *
   * @param arrayOctet byte array to test
   * @return <code>true</code> if all bytes are valid characters in the Base64 alphabet or if the
   * byte array is empty;
   * false, otherwise
   */
  public static boolean isArrayByteBase64(byte[] arrayOctet) {
    for (int i = 0; i < arrayOctet.length; i++) {
      if (!isBase64(arrayOctet[i]) && !isWhiteSpace(arrayOctet[i])) {
        return false;
      }
    }
    return true;
  }

  /**
   * Tests a given byte array to see if it contains only valid characters within the Base64
   * alphabet.
   *
   * @param arrayOctet byte array to test
   * @return <code>true</code> if any byte is a valid character in the Base64 alphabet; false
   * herwise
   */
  private static boolean containsBase64Byte(byte[] arrayOctet) {
    for (byte element : arrayOctet) {
      if (isBase64(element)) {
        return true;
      }
    }
    return false;
  }

  /**
   * Encodes binary data using the base64 algorithm but does not chunk the output.
   *
   * @param binaryData binary data to encode
   * @return byte[] containing Base64 characters in their UTF-8 representation.
   */
  public static byte[] encodeBase64(byte[] binaryData) {
    return encodeBase64(binaryData, false);
  }

  /**
   * Encodes binary data using the base64 algorithm into 76 character blocks separated by CRLF.
   * <p>
   * For a non-chunking version, see {@link #encodeBase64StringUnChunked(byte[])}.
   *
   * @param binaryData binary data to encode
   * @return String containing Base64 characters.
   * @since 1.4
   */
  public static String encodeBase64String(byte[] binaryData) {
    return newStringUtf8(encodeBase64(binaryData, true));
  }

  /**
   * Encodes binary data using the base64 algorithm, without using chunking.
   * <p>
   * For a chunking version, see {@link #encodeBase64String(byte[])}.
   *
   * @param binaryData binary data to encode
   * @return String containing Base64 characters.
   * @since 3.2
   */
  public static String encodeBase64StringUnChunked(byte[] binaryData) {
    return newStringUtf8(encodeBase64(binaryData, false));
  }

  /**
   * Encodes binary data using the base64 algorithm.
   *
   * @param binaryData binary data to encode
   * @param useChunking whether to split the output into chunks
   * @return String containing Base64 characters.
   * @since 3.2
   */
  public static String encodeBase64String(byte[] binaryData, boolean useChunking) {
    return newStringUtf8(encodeBase64(binaryData, useChunking));
  }

  /**
   * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the
   * output. The
   * url-safe variation emits - and _ instead of + and / characters.
   *
   * @param binaryData binary data to encode
   * @return byte[] containing Base64 characters in their UTF-8 representation.
   * @since 1.4
   */
  public static byte[] encodeBase64URLSafe(byte[] binaryData) {
    return encodeBase64(binaryData, false, true);
  }

  /**
   * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the
   * output. The
   * url-safe variation emits - and _ instead of + and / characters.
   *
   * @param binaryData binary data to encode
   * @return String containing Base64 characters
   * @since 1.4
   */
  public static String encodeBase64URLSafeString(byte[] binaryData) {
    return newStringUtf8(encodeBase64(binaryData, false, true));
  }

  /**
   * Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character
   * blocks
   *
   * @param binaryData binary data to encode
   * @return Base64 characters chunked in 76 character blocks
   */
  public static byte[] encodeBase64Chunked(byte[] binaryData) {
    return encodeBase64(binaryData, true);
  }

  /**
   * Decodes a String containing containing characters in the Base64 alphabet.
   *
   * @param pArray A String containing Base64 character data
   * @return a byte array containing binary data
   * @since 1.4
   */
  public byte[] decode(String pArray) {
    return decode(getBytesUtf8(pArray));
  }

  private byte[] getBytesUtf8(String pArray) {
    try {
      return pArray.getBytes("UTF8");
    } catch (UnsupportedEncodingException e) {
      throw new RuntimeException(e);
    }
  }

  /**
   * Decodes a byte[] containing containing characters in the Base64 alphabet.
   *
   * @param pArray A byte array containing Base64 character data
   * @return a byte array containing binary data
   */
  public byte[] decode(byte[] pArray) {
    reset();
    if (pArray == null || pArray.length == 0) {
      return pArray;
    }
    long len = (pArray.length * 3) / 4;
    byte[] buf = new byte[(int) len];
    setInitialBuffer(buf, 0, buf.length);
    decode(pArray, 0, pArray.length);
    decode(pArray, 0, -1); // Notify decoder of EOF.

    // Would be nice to just return buf (like we sometimes do in the encode
    // logic), but we have no idea what the line-length was (could even be
    // variable).  So we cannot determine ahead of time exactly how big an
    // array is necessary.  Hence the need to construct a 2nd byte array to
    // hold the final result:

    byte[] result = new byte[pos];
    readResults(result, 0, result.length);
    return result;
  }

  /**
   * Encodes binary data using the base64 algorithm, optionally chunking the output into 76
   * character blocks.
   *
   * @param binaryData Array containing binary data to encode.
   * @param isChunked if <code>true</code> this encoder will chunk the base64 output into 76
   * character blocks
   * @return Base64-encoded data.
   * @throws IllegalArgumentException Thrown when the input array needs an output array bigger than
   * {@link Integer#MAX_VALUE}
   */
  public static byte[] encodeBase64(byte[] binaryData, boolean isChunked) {
    return encodeBase64(binaryData, isChunked, false);
  }

  /**
   * Encodes binary data using the base64 algorithm, optionally chunking the output into 76
   * character blocks.
   *
   * @param binaryData Array containing binary data to encode.
   * @param isChunked if <code>true</code> this encoder will chunk the base64 output into 76
   * character blocks
   * @param urlSafe if <code>true</code> this encoder will emit - and _ instead of the usual + and /
   * characters.
   * @return Base64-encoded data.
   * @throws IllegalArgumentException Thrown when the input array needs an output array bigger than
   * {@link Integer#MAX_VALUE}
   * @since 1.4
   */
  public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe) {
    return encodeBase64(binaryData, isChunked, urlSafe, Integer.MAX_VALUE);
  }

  /**
   * Encodes binary data using the base64 algorithm, optionally chunking the output into 76
   * character blocks.
   *
   * @param binaryData Array containing binary data to encode.
   * @param isChunked if <code>true</code> this encoder will chunk the base64 output into 76
   * character blocks
   * @param urlSafe if <code>true</code> this encoder will emit - and _ instead of the usual + and /
   * characters.
   * @param maxResultSize The maximum result size to accept.
   * @return Base64-encoded data.
   * @throws IllegalArgumentException Thrown when the input array needs an output array bigger than
   * maxResultSize
   * @since 1.4
   */
  public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe,
      int maxResultSize) {
    if (binaryData == null || binaryData.length == 0) {
      return binaryData;
    }

    long len = getEncodeLength(binaryData, isChunked ? CHUNK_SIZE : 0,
        isChunked ? CHUNK_SEPARATOR : EMPTY_BYTE_ARRAY);
    if (len > maxResultSize) {
      throw new IllegalArgumentException("Input array too big, the output array would be bigger ("
          + len
          + ") than the specified maxium size of "
          + maxResultSize);
    }

    Base64 b64 = isChunked ? new Base64(urlSafe) : new Base64(0, CHUNK_SEPARATOR, urlSafe);
    return b64.encode(binaryData);
  }

  /**
   * Decodes a Base64 String into octets
   *
   * @param base64String String containing Base64 data
   * @return Array containing decoded data.
   * @since 1.4
   */
  public static byte[] decodeBase64(String base64String) {
    return new Base64().decode(base64String);
  }

  /**
   * Decodes Base64 data into octets
   *
   * @param base64Data Byte array containing Base64 data
   * @return Array containing decoded data.
   */
  public static byte[] decodeBase64(byte[] base64Data) {
    return new Base64().decode(base64Data);
  }

  /**
   * Checks if a byte value is whitespace or not.
   *
   * @param byteToCheck the byte to check
   * @return true if byte is whitespace, false otherwise
   */
  private static boolean isWhiteSpace(byte byteToCheck) {
    switch (byteToCheck) {
      case ' ':
      case '\n':
      case '\r':
      case '\t':
        return true;
      default:
        return false;
    }
  }

  /**
   * Encodes a byte[] containing binary data, into a String containing characters in the Base64
   * alphabet.
   *
   * @param pArray a byte array containing binary data
   * @return A String containing only Base64 character data
   * @since 1.4
   */
  public String encodeToString(byte[] pArray) {
    return newStringUtf8(encode(pArray));
  }

  private static String newStringUtf8(byte[] encode) {
    String str = null;
    try {
      str = new String(encode, "UTF8");
    } catch (UnsupportedEncodingException ue) {
      throw new RuntimeException(ue);
    }
    return str;
  }

  /**
   * Encodes a byte[] containing binary data, into a byte[] containing characters in the Base64
   * alphabet.
   *
   * @param pArray a byte array containing binary data
   * @return A byte array containing only Base64 character data
   */
  public byte[] encode(byte[] pArray) {
    reset();
    if (pArray == null || pArray.length == 0) {
      return pArray;
    }
    long len = getEncodeLength(pArray, lineLength, lineSeparator);
    byte[] buf = new byte[(int) len];
    setInitialBuffer(buf, 0, buf.length);
    encode(pArray, 0, pArray.length);
    encode(pArray, 0, -1); // Notify encoder of EOF.
    // Encoder might have resized, even though it was unnecessary.
    if (buffer != buf) {
      readResults(buf, 0, buf.length);
    }
    // In URL-SAFE mode we skip the padding characters, so sometimes our
    // final length is a bit smaller.
    if (isUrlSafe() && pos < buf.length) {
      byte[] smallerBuf = new byte[pos];
      System.arraycopy(buf, 0, smallerBuf, 0, pos);
      buf = smallerBuf;
    }
    return buf;
  }

  /**
   * Pre-calculates the amount of space needed to base64-encode the supplied array.
   *
   * @param pArray byte[] array which will later be encoded
   * @param chunkSize line-length of the output (<= 0 means no chunking) between each
   * chunkSeparator (e.g. CRLF).
   * @param chunkSeparator the sequence of bytes used to separate chunks of output (e.g. CRLF).
   * @return amount of space needed to encoded the supplied array.  Returns
   * a long since a max-len array will require Integer.MAX_VALUE + 33%.
   */
  private static long getEncodeLength(byte[] pArray, int chunkSize, byte[] chunkSeparator) {
    // base64 always encodes to multiples of 4.
    chunkSize = (chunkSize / 4) * 4;

    long len = (pArray.length * 4) / 3;
    long mod = len % 4;
    if (mod != 0) {
      len += 4 - mod;
    }
    if (chunkSize > 0) {
      boolean lenChunksPerfectly = len % chunkSize == 0;
      len += (len / chunkSize) * chunkSeparator.length;
      if (!lenChunksPerfectly) {
        len += chunkSeparator.length;
      }
    }
    return len;
  }

  // Implementation of integer encoding used for crypto

  /**
   * Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
   *
   * @param pArray a byte array containing base64 character data
   * @return A BigInteger
   * @since 1.4
   */
  public static BigInteger decodeInteger(byte[] pArray) {
    return new BigInteger(1, decodeBase64(pArray));
  }

  /**
   * Encodes to a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
   *
   * @param bigInt a BigInteger
   * @return A byte array containing base64 character data
   * @throws NullPointerException if null is passed in
   * @since 1.4
   */
  public static byte[] encodeInteger(BigInteger bigInt) {
    if (bigInt == null) {
      throw new NullPointerException("encodeInteger called with null parameter");
    }
    return encodeBase64(toIntegerBytes(bigInt), false);
  }

  /**
   * Returns a byte-array representation of a <code>BigInteger</code> without sign bit.
   *
   * @param bigInt <code>BigInteger</code> to be converted
   * @return a byte array representation of the BigInteger parameter
   */
  static byte[] toIntegerBytes(BigInteger bigInt) {
    int bitlen = bigInt.bitLength();
    // round bitlen
    bitlen = ((bitlen + 7) >> 3) << 3;
    byte[] bigBytes = bigInt.toByteArray();

    if (((bigInt.bitLength() % 8) != 0) && (((bigInt.bitLength() / 8) + 1) == (bitlen / 8))) {
      return bigBytes;
    }
    // set up params for copying everything but sign bit
    int startSrc = 0;
    int len = bigBytes.length;

    // if bigInt is exactly byte-aligned, just skip signbit in copy
    if ((bigInt.bitLength() % 8) == 0) {
      startSrc = 1;
      len--;
    }
    int startDst = bitlen / 8 - len; // to pad w/ nulls as per spec
    byte[] resizedBytes = new byte[bitlen / 8];
    System.arraycopy(bigBytes, startSrc, resizedBytes, startDst, len);
    return resizedBytes;
  }

  /**
   * Resets this Base64 object to its initial newly constructed state.
   */
  private void reset() {
    buffer = null;
    pos = 0;
    readPos = 0;
    currentLinePos = 0;
    modulus = 0;
    eof = false;
  }

  // Getters for use in testing

  int getLineLength() {
    return lineLength;
  }

  byte[] getLineSeparator() {
    return lineSeparator.clone();
  }
}
